Enclosed Trailer Insulation

[hadfield4wd]

A friend has a brand new gorgeous enclosed trailer.  It has plywood walls a on the interior, windows and prewired for 110v.  I'm going to assist with a buildout.  Steop one is insulation.  Is there a way to insulate it without removing the plywood?  It's screwed and glued.  I'm thinking sprayfoam with a couple holes drilled so it can expand.  Any thoughts or concerns with this?

 

 

Edited September 14, 2018 by hadfield4wd

[Betarocker]

If you use spray foam, you NEED to remove the plywood. That stuff expands a lot and will make the skin buckle out more than what the image shows now. 

[SnowMule]

I've looked into spray foam for several trailer builds. 

Consensus has always been, for the walls/ceiling, not worth it.  Either it doesn't fill in all the way and leaves a thin spot, or it fills in too much and you have to trim it and/or it bows out the exterior tin.  Really hard to control the expansion.

For the floor underneath and in oddball corners, it's terrific. 

In the walls, use foil-backed iso board.  It's cheap, cuts easy, and works just as well as spray foam.  Depending on how crazy you get with the rebuild, you might need to shoot some Great-Stuff foam in the edges of the walls to lock the foam boards in place and seal drafts. 

Plywood down, insulation in, spray-foam-in-a-can the gaps, do your wiring, plywood back up.

 

Same thing in the ceiling.

 

Same stuff in the big trailer.  Works great.  (We did remove both interior and exterior walls on this project, so we were able to cut the foam exactly to length/width, stuff it in with no gaps.)

 

Underside got shot with about 6" of foam.  Makes the floor sound less trailery/hollow and more solid.  Keeps the interior at a more even temperature - don't have the big gradient from top to bottom.

 

Shot some areas in the goose that would have been awkward to fill in with iso board. 

[Orange Crush 500]

Looks good

[hadfield4wd]

Dang we didn't want to remove the plywood. Looks like its inevitable.

[SnowMule]

It's not that big of a deal.

[C-M]

There are companies out there that offer a foam that they pump into walls but they cut a 2 " or so hole in the wall top and bottom then pump the foam until it comes out the bottom they use it in houses it is not to expensive and should be cheaper since you can take the trailer to them, saving them transportation of the equipment to your home, sorry I do not have any company info for you.

[SnowMule]

In houses, ther'es more structure/rigidity to the walls, and the 2x4's encapsulate everything well.  Don't have that luxury with trailers.

 

When I was shopping around for my trailer, I found a lot of companies that were more than happy to sell you foam kits, "Oh yeah this stuff works great everywhere, easy to DIY, we've done everything, buy our stuff!!"... then I found a foam company who wanted to see the job done right.  They had a fleet of trailers, they shot half with foam before realizing it just didn't work to the quality most people expect out of it.  The rest of their fleet they insulated with foam board. 

[BlackBuzzard]

Not saying it shouldn't be done, but you're  still going to get very hot or very cold depending on weather.

Cold you can dress for and/or use a Mr Buddy heater.....use a CO detector!

Heat?   Well  either suffer or run a gen with an AC on......sometimes all night.

 

Funny how all those solar panel advocates always seem to have a Honda generator tucked away somewhere in the trailer.

 

 

 

[Missouri Railroader]

Take the ply wood down. Use the foam foil backed insulation. I cut mine with a jig saw worked awesome. Cut them tight enough the pressure will hold them in. Then i took actual hvac duct tape and taped over all the seams.

[Dirtbug26]

IMO you will never insulate a trailer good enough to make a big difference, the walls are too thin. Save your time and money, and run the A.C. when hot and propane heater when cold. 

[SnowMule]

13 hours ago, Dirtbug26 said:

IMO you will never insulate a trailer good enough to make a big difference, the walls are too thin. Save your time and money, and run the A.C. when hot and propane heater when cold. 

I definitely beg to differ. 

As much insulation as you can get in there, seal up the gaps, then use A/C or furnace as necessary. 

With the big trailer, all the insulation in there really paid off.  Most trailers are warm up top and cooler at the bottom because they leak so much heat; this one's much more uniform temp throughout.  1" in the walls, 2.5" in the ceiling, and 6" under the floor.